The mists were created from the wild Gypsy Morph magic of Hawk.
It kept the survivors of the Great Wars safely inside, and whatever was outside out. They appeared as a grey nothingness. Trying to get through them was futile – no matter how straight a path you took through them they would always turn you around again, leaving you back where you had started from.1Bearers of the Black Staff – p 3
The mists protecting them would not protect them forever, although some people believed they would.
The various races separated shortly after their arrival, even before the mists were created, moving away to establish their own boundaries. Humans settled in the south and west; the Elves in the north-east, and the Lizards and Spiders, with their much lower numbers, settled in small corners in between. The valley made this separation more defined as it was actually a series of smaller valleys separated by natural features such as woods, hills, lakes, rivers and smaller mountain ranges.
When the valley was first settled it took a while for the communities to establish an order to things, but once they had settled it trade flourished. The Humans would trade between their villages for what was needed, and if required they would also trade with the Elves and Lizards.
Being confined did not trouble anyone for most of the time they were there, but eventually some tension did begin to build. The Children of the Hawk sect was a human creation, and the other Races did not believe in its teachings. The Elves believed it was their duty to go back out into the world and restore it to its condition before the Great Wars. The Lizards were nomads, the Spiders were deeply reclusive.
Kodens could be found in the Valley.